I recently upgraded from my Giant Power Pro dual-sided crank-based power meter to the Favero Assioma PRO RS-2 pedals.
I’ve noticed that the Assioma consistently reports around 6–7% lower power. I compared both power meters by recording data simultaneously during the same rides and on the same segments.
During intervals above 300 W, the difference is often more than 20 W.
Today I also rode several climb segments with a friend who weighs about the same as I do and uses Garmin Rally RS200 pedals. Again, the Assioma reported significantly lower power, with an even larger difference. On one 2-minute climb, for example, his Garmin showed 480 W, while my Assioma showed only 400 W.
Has anyone experienced something similar?
I was under the impression that Favero was considered one of the benchmark power meters, but these comparisons are starting to make me question whether my unit is measuring correctly.
P.S. The pedals were installed exactly according to the instructions, the firmware is up to date, and I performed a calibration (zero offset) before testing.
I have single sided Favero pedals which read about 5% lower than both my Kickr Cores at 150 Watts and 15-20% lower at 400 Watts. I had Garmin Vector 3s that I wore out before buying the Assiomas and they read similarly low compared to the Kickrs. I assume I’m dominant on my right side, struggle to believe there can be 10% difference between my right and left legs, but have no other explanation to offer…
FWIW: I have Duos and my avg L/R balance varies from ride to ride. Recently it’s been 58/42, 53/47, 57/43, 56/44… I have a spider PM on my mtb and it estimates L/R balance at, 52/48, 54/46, 54/46, 53/47…I have no obvious physical asymmetry that would suggest I’d not be 50/50.
Very interesting ratios, thanks for sharing. I hadn’t expected such variability between legs or even considered variability between rides. Duos next time!
Mine doesn’t vary between rides, but it does between zones.
Anything above sweet spot, I’m very close to 50:50. As soon as the power drops lower than sweet spot it starts to drift and my recovery intervals can be as far off as 43:57!
You can’t compare your power to your friend’s power. Faveros, in my experience, have been extremely accurate. They are also the PM many reviewers use as their benchmark.
Favero are generally pretty accurate. Shimanos used to have a lot of issues / error - not sure if that’s what Giant is.
Make sure crank length is set correctly in your head unit if that’s what you’re using to measure power. That will override settings in the Favero App. An App like TR doesn’t have that option so I think it defaults back to the last used setting.
Recently got a new climbing bike and put exact same power meters on it. I have concluded that they read 3-4% low (compared to Quarq). They seemed to be reading low and confirmed this by comparing Mt Kearsarge climb time with last year (23:06, 290 watts this year, 22:48, 304 watts last year, different bike - 1 lb lighter this year, no difference in wind); compared recent interval efforts by looking at earlier efforts on same Strava segment with exact same time - recent average of 2 efforts with same time to earlier average of 10 efforts with that same time was 330 to 344; recent single effort to earlier average of 15 efforts with that same time was 323 to 332. Correct crank length everywhere; calibrated; firmware updated at installation (3 weeks ago) and then today. My conclusion right now is that readings are about 10 watts lower at 300 watts. Not sure if today’s firmware update has changed anything.
Here’s another potential: Your Quarq powermeters read 3-4% high, and the Favero is correct
I deal with the same thing, and at the end of the day it doesn’t matter as long as everything is consistent. I have all my Quarqs and my Faveros calibrated to read the same (or as close as possible)
Sounds like you’re comparing the Assioma pedals to historic Quarq data. Is it possible to put the pedals on a bike with the Quarq and record both to do a direct comparison, or do you no longer have the Quarq? Are both double sided? I just got a new bike and put a Quarq spider on it. I’ll soon put my Assioma Duos on it and do a direct comparison between them.
Favero’s are good, but not perfect. Honest answer is no way to tell which is most “Accurate” but I’d lean towards Favero. The good thing is - accuracy doesn’t matter much, consistency does.
My experience has been two groups: 1 x Favero, 3 x Quarq, 1 x Garmin Rally, 1 x Neo 2T all read very close which is what I use as my “benchmark”
The second group: 1 x Favero, 1 x Quarq, 1 x TacX Neo 3M that read ~3-4% lower (maybe a little less)
All data from Dual or Triple Recording - mostly on the trainer but outside too.
Shimano used to have a lot of issues - I wouldn’t trust them.
